In the related art, an MFP (multi-function peripheral) or other image-forming apparatus is employed to form an image on a sheet (paper sheet). To erase the image formed on the sheet so that the sheet is available for reuse, the image is printed on the sheet using an ink containing leuco dye or another erasable coloring agent.
The erasable coloring agent can be erased when heated to a high temperature. Consequently, when the sheet is to be reused, an erasing apparatus is employed to heat the sheet so that the image formed on the sheet is erased. In the erasing apparatus, a heating roller and a pressing roller are arranged facing each other with the conveying path of the sheet held between them. As the sheet is conveyed between the heating roller and the pressing roller, the sheet is heated so that the erasable coloring agent is erased. Here, the erasing section including a heating roller and a pressing roller is arranged on both the upstream side and downstream side along the conveying path of the sheet so that both sides of the sheet can be erased. Usually, the heating rollers and pressing rollers arranged on the upstream side and the downstream side have the same diameter.
The sheet conveyed in the erasing apparatus is heated by the upstream erasing section and then conveyed to the downstream erasing section. Consequently, for the downstream side, there is no need to have the same heat capacity as the upstream side. As a result, when the heating roller and pressing roller arranged on the upstream side and the rollers arranged on the downstream side have the same diameter and heating quantity, the arrangement of the downstream side becomes wastefully larger, and the power consumption is increased unnecessarily.